1. The Field of the Invention
The present invention pertains to wheeled land vehicles which are propelled by human power. More particularly, the present invention is directed to a wheeled human powered land vehicle for carrying at least one operator who propels the vehicle by use of his arms and torso moved in a reciprocating back and forth fashion.
2. The Prior Art
Over the past three centuries wheelchairs have been used by individuals whose legs are not capable of functioning normally or are absent. Many of these individuals are otherwise active and healthy members of society. However, due to their nonfunctioning, or absent, legs, they are not able to participate in activities which require locomotion by use of the legs.
However, participating in vigorous physical exercise for these handicapped individuals can be more important than for individuals having full use of their four limbs. Thus, various athletic activities for people confined to a wheelchair have been devised.
Many individuals engage in such "wheelchair sports" for purely recreational pleasure. However, some individuals have organized groups specifically to engage in wheelchair sports on a competitive level. Many of these "wheelchair athletes" are excellent athletes even though they do not have the use of their lower limbs. One of the wheelchair sports which has attracted a great deal of attention, both from handicapped individuals and the general public, is wheelchair racing.
During the past fifteen years, many changes have taken place within the ranks of racing wheelchair athletes. Since 1957, when the National Wheelchair Athletic Association (NWAA) was formed, racing wheelchairs have evolved from being limited to large and heavy models, such as the "standard" models manufactured by Everest and Jennings.RTM. or their equivalents, to the point today when racing wheelchairs are custom fabricated of lightweight materials to meet the particular needs of the wheelchair athlete's body. The design of these racing wheelchairs helps the athlete to better use his available muscle strength and weight. Furthermore, the development of lightweight materials and more efficient designs for wheelchairs has also benefited those who do not participate in wheelchair athletics.
At one time it was thought that racing wheelchairs should all be of the same design so as to avoid giving a particular athlete an advantage because of his wheelchair. However, over the years the decisions of the NWAA have allowed a more flexible approach to the design and construction of racing wheelchairs. This more flexible approach has focused on maximizing an athlete's individual strengths rather than limiting the athlete to the use of a standardized set of equipment. This approach taken by the NWAA has resulted in significant changes, as mentioned earlier, to racing wheelchairs. In turn, these significant changes have resulted in faster, and safer, wheelchairs and correspondingly faster finishing times in all categories of races.
Initially, when wheelchair races were first seriously organized, races generally consisted of 40, 60, and 100 yard dashes. Today, however, wheelchair races now include short, medium, and long distance events, including marathons (26+ miles) which may traverse varying terrain over the open road. Also, many wheelchair athletes do not desire to compete in a race but still desire to independently travel long distances over the open road. Such long distance travel is also referred to as "touring."
Even though the improvement in wheelchair design and materials over the past three decades has greatly improved the performance of wheelchair athletes, even the newest improved chair is basically the same chair that was in use more than 100 years ago. Modern racing wheelchairs are built with lightweight materials, larger wheels, smaller push-rims, lower seats, and high knee posture all of which provide for a more stable and efficient design for the athlete. But the basic design of the modern racing wheelchair is clearly similar to the designs commonly found throughout the past three centuries.
Even with the racing wheelchairs that incorporate all the improvements of the prior art, racing wheelchairs still retain the basic problems of less than optimum muscle use, restricted breathing due to the "crouched" posture of the athlete, and no mechanical system to multiply the rider's strength. Even those designs which have been intended to increase the efficiency of the wheelchair do not lend themselves to use in a racing wheelchair.
For example, one design found in the existing art adapts a conventional four wheel wheelchair by attaching ratcheting levers connected to each wheel along the side of the chair. The rider causes the chair to move forward by grasping the levers and moving the levers back and forth parallel to the circumference of the wheels. Such a design uses the arm and upper body strength of a wheelchair athlete relatively inefficiently and does not provide any advantage over the racing wheelchair designs otherwise available in the art. Thus, wheelchair athletes generally choose wheelchairs which are lightweight modified versions of an ordinary wheelchair.
In summary, while the standard wheelchair serves the ordinary needs of the handicapped adequately, the racing wheelchair athlete often finds that the available adaptations of the conventional wheelchair to his particular needs makes less than optimum use of his athletic ability. Thus, it would be a significant advance in the art of wheelchair design to provide a vehicle with which a paraplegic or lower limb amputee operator could efficiently propel himself using his arms and torso.
It would be a further advance in the art to provide such a vehicle in which the efficiency of the vehicle is maximized so as to make best use of the strength of the operator according to the particular circumstances in which the operator finds himself, that is, racing on a track or on the open road through uneven terrain. A wheeled land vehicle which can be propelled by the motion of the arms and torso of the operator would be welcomed by many wheelchair athletes.